Automated belt cooking machines have been used in the prior art to cook certain food products, such as pancakes, meat patties, and fillets of fish and chicken. The prior art includes single belt cooking machines, particularly of the bar type or open mesh conveyor type, series belt cooking machines, and overlapping belt cooking machines. Single belt cooking machines, though commonplace, are illsuited for cooking food products that require the application of heat to the top and bottom of the food to be cooked.
Where such attempts have been made with single belt cooking machines utilizing overlapping platens to heat the top and bottom of the food along the run of the belt, as in U.S. Pat. No. 3,965,807 and U.S. Pat. No. 3,739,711, a single conveyor pushes the food to be cooked over a lower platen and under an upper platen so that direct thermal contact between the platens and the food is achieved. However, where the food to be cooked consists of, or includes, a bubble forming substance, such as batter, bubbles are formed between the platens and the gases trapped therewithin are prevented from being released peacefully from the top of the food being cooked by pressure exerted against the expanding food by the upper platen. Instead the gases are likely to be released violently from the sides or bottom of the food being cooked, lending to a disrupted structure of the cooked food. Furthermore, the direct contact between the platens and the food and the likely bursting of bubbles requires that the platens be cleaned regularly, meaning that the machinery will suffer down-time resulting in lost productivity during a cool down and cleaning period. Also, the open structure of the single conveyor used in the above patents means that the food is likely to break up or become embedded in the open structure, therefore requiring cleaning of the conveyor and surrounding structures to remove the baked on fragments of the food.
Where attempts have been made with series belt cooking machines to cook food products that require the application of heat to the top and bottom of the food to be cooked, as in U.S. Pat. No. 4,667,589 and No. 5,077,072 the food is initially cooked on an underside as it passes on an upper conveyor and is then flipped onto a lower conveyor wherein it is cooked on the opposite side, optionally followed by flattening the cooked food by sandwiching between belts. As such attempts require at least two flights of conveyors and a flipping manoeuvre to transfer the food from one conveyor to another, the machinery needed to achieve the desired cooked food product is more complicated and prone to failure than overlapping belt cooking machines.
Where attempts have been made with overlapping belt cooking machines to cook food products that require the application of heat to the top and bottom of the food to be cooked, as in U.S. Pat. No. 5,044,264 and U.S. Pat. No. 5,458,051, a pair of opposed, counter-rotating belts, particularly of the Teflon coated over fibreglass fabric type, convey the food between heated upper and lower platens which are in thermal contact with the portions of the upper and lower belts respectively that make contact with the food, so that heat generated by the platens is conducted through the belts and into the top and bottom of the food to be cooked. However, the superimposed location of the upper and lower platens is such that the food to be cooked is exposed to heat conducted through both the upper and lower belts simultaneously, and the parallel disposition of the upper and lower platens is such that no allowance is made for the usual increase in thickness of the food as it is being cooked between the platens. The simultaneous application of heat to the top and bottom surfaces of the food whilst the food is sandwiched and conveyed between the counter-rotating belts does not allow, it is assumed, for the gradual and peaceful release of gases trapped in bubbles formed on the surface of the food, particularly from the top of the food, causing disruption of the interior and surface structure of the food product as the bubbles burst out of the sides of the food.
It is an object of the present invention to overcome, or at least substantially ameliorate, the disadvantages and shortcomings of the prior art.